[Analysis for dropout of DTaP routine immunization in China in 2019]

Objective: To analyze the dropout of adsorbed diphtheria, tetanus and acellular pertussis combined vaccine (DTaP) routine immunization in China in 2019. Methods: DTaP vaccination data in all counties in China were collected through National Immunization Program Information Management System in 2019. Cumulative dropout rate and vaccination rate of DTaP in different provinces were calculated. According to the P₂₅, P₅₀ and P₇₅ values of DTaP dropout rate for all counties by province, counties in each province were divided into four groups (Q₁-Q₄). The DTaP average dropout rate of four groups and absolute difference (difference in DTaP average dropout rate between Q₄ and Q₁) were calculated. Spearman rank correlation was used to analyze the relationship between absolute difference and provincial DTaP dropout rate, DTaP₁ and DTaP₃ vaccination rate. Results: DTaP₁ vaccination rate ranged from 92.98% to 99.94% by province, with a median of 99.55%. Provincial DTaP dropout rate ranged from 0.36% to 28.66%, with a median of 3.54%. The provincial DTaP dropout rate was more than 10% in Gansu and Guizhou, about 28.66% and 17.19%. Absolute difference ranged from 4.02% to 39.22%, with a median of 10.16%. Provinces with the largest absolute difference were Gansu, Qinghai, Liaoning and Guizhou, about 39.22%, 34.48%, 23.31% and 21.33%, respectively. Correlation analysis indicated that the absolute difference was positively correlated with provincial DTaP dropout rate, with a correlation coefficient of 0.492 (P=0.004). It was negatively correlated with DTaP₁ and DTaP₃ vaccination rate. Correlation coefficients were -0.542 (P=0.001) and -0.562 (P=0.001), respectively. Conclusions: There are significant county-level differences in DTap dropout rate in most provinces, with relatively high difference in western provinces.